Abstract
Purpose: :
Spectral-domain optical coherence tomography (SD-OCT), a recent advance in retinal imaging, acquires large number of A-scans in a short duration (40,000 A-scans/second) and provides high resolution cross-sectional images of the retina. For better evaluation of retinal pathology, it is important to establish the normative data parameters of the retina for accurate comparison. The purpose of this study is to establish normative data for macular thickness by SD-OCT in subjects with no known retinal disease.
Methods: :
In a prospective study, approved by the Institutional Review Board, 65 subjects (age range 20-84 years) with no known retinal disease and best-corrected visual acuity of 20/20 were included in the study. The subjects were divided into 3 age groups: group 1, ages 20-40 years; group 2, ages 41-60 years: and group 3, age 61 years and above. Both eyes of the subjects were scanned by SD-OCT and all scans were performed by a single operator. Data from the right eye were analyzed by default, unless the right eye had to be excluded. Parameters measured were central point thickness (CPT) and retinal thickness in 9 ETDRS subfields including central subfield (CSF). Statistical analyses were done using the ANOVA test.
Results: :
Overall, the mean CPT was 227.8 ± 21.8 µm and mean CSF was 271.3 + 22.1 µm. Among the ETDRS subfields, the outer nasal quadrant had the maximum thickness (Mean + standard deviation = 341.9 + 17.5 µm). The retinal thickness did not show significant change with age (p=0.62) or with gender (p=0.1). However, there was a suggestion of significant change in retinal thickness with respect to the race of the patient (p=0.007).
Conclusions: :
Macular thickness in healthy normal eyes was measured to be 227.8 µm (CPT) and 271.3 µm (CSF) using commercially available Spectralis SD-OCT. Based on the macular thickness measurements and standard deviation, the present study proposes the guidelines for normal central subfield thickness to be 315 µm for future studies, utilizing macular thickness measurements with Spectralis SD-OCT.
Keywords: retina • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical